Use of methylene polyphenols for improving physical properties of clays and clay-containing materials and compositions resulting therefrom



United States Patent 0 This invention concerns compositions and methods for the treatment of clays and clay-containing soils having at least weight percent clay, dry basis, with a methylene.

polyphenol compound (hereafter MPP) having the formula:

lih R R4 in which X is one of H and CH R and R individually are one of H and alkyl having up to 4 carbon atoms; R is one of H, Cl and alkyl having up to 4 carbon atoms; and n is an integer from 0 to 1. The invention particularly concerns treating clays and clayey soils for use in making strong and structurally stable roadways and clayderived structural materials, and for the controlled fracturing of crust-forming soils in agriculture.

Clays and clay-containing materials are found naturally in various geological deposits, including soil. These materials have the properties of being dimensionally unstable and of forming fluid cohesive and adhesive mixtures in the presence of water. Conversely, upon drying, these materials become extremely stress resistant. While many of the uses of clays, clay soils and other clay-containing materials depend upon these properties, such properties are a distinct handicap in other uses.

Thus, when clays or clay-containing soils are used as integral constituents of the foundation, grade, base or structure in the construction of highways, runways, dams and buildings, the problem often arises that the clay-containing material loses a significant portion of its strength or load-bearing capacity in the presence of moisture or water. This is true even of materials which have been treated with common solidifying agents such as Portland cement or lime.

Clay-containing soils which have been exposed to rain or irrigation water and subsequently dried often will form crusts through which plant penetration is very diflicult or impossible.

In the past it has been the practice to avoid the use of these clay-containing materials, to compensate for their shortcomings byother methods, or to use them in spite of their shortcomings. Thus, in the construction industry where it is desired to make use of local soils or aggregate, the presence of excessive amounts of clay in these materials has necessitated the hauling in of materials from other locations. This operation is expensive and, furthermore, suitable materials are frequently scarce. Another alternative has been to process the clay-containing aggre-s gate so as to remove the clay. Again, this is an expensive Patented May 12, 1964 procedure and is not always practical. Other alternative procedures involve using engineering techniques such as reinforced concrete, extra thick bases and grades, and pilings to compensate for the inferior properties of the clay-containing materials. These techniques, however, also are expensive. The final alternative is to maintain construction costs at a minimum and to use the inferior clay-containing materials. This, of course, results in increased maintenance costs throughout the years.

For agricultural purposes, it is impossible to avoid the use of a clay-containing soil where it exists, except to retire it from agricultural production. Frequently, however, -the crusting problem with such soils is mitigated by the use of crops which are more capable of penetrating through crusts, or by planting several seeds together so that by their combined eifort at least 'one plant will emerge, or by transplanting seedlings, in which case the plant does not need to penetrate the crusted soil surface. In many cases these are quite satisfactory solutions to the crusting problem. In other cases, however, these techniques impose restrictions on the grower that he would prefer to avoid. The other alternative used, of course, is to proceed in the hope that conditions necessary to crust formation do not occur before the plants have penetrated the soil surface. While this is frequently the case, these are numerous times when it is not, and severe losses to the farmer result. Thus, there is a definite need for clay, clay soils and other clay-containing materials for use as structural material precursors, which, in the presence of water, have the properties of enhanced dimensional stability and of forming less cohesive and adhesive fluid mixtures, but which, when dried, have the property of less stress resistance than such soils or materials when untreated. Such treated clays, soils and other clay-containing materials can be considered to be less water sensitive than the corresponding untreated materials.

This invention is concerned with the treatment of clays and clay-containing soils having at least 5 weight percent, dry basis, of a naturally occurring clay, e.g., of the kaolinitic, montmorillonitic, illitic or mixed layer type, with a MPP compound, as specified above, in an amount ranging between about 0.0025 and 2 weight percent, dry clay basis, to improve their physical properties for agricultural purposes. An auxiliary solidifying or bonding agent such as lime, asphalts (black to dark brown solid or semisolid cementitious hydrocarbons which gradually liquefy when heated, the predominant constituents of which are bitumen), sodium silicates having a silica to soda ratio (SiOg:Na O) in the range of 1.69:1 to 3.90:1 or Portland cement in amount from 1 to weight percent, clay basis, is advantageous in making structural materials.

By way of illustration, the following sorts of MPP compounds can be used in the practice of this invention:

m nt bis(5 tert-butyl-6-hydroxy-m-tolyl)-4-chloro-2,6-

. xylenol 6,6'-methylenedi-2,4-xylenol 2,2'-ethylidenebis(6-tert-butyl-p-cresol) The MPP compound can be applied to the clay or claycontainingsoil or material in several ways. The preferred way involves dispersing the MPP compound either as a suspension or as a solution in a liquid medium and admixing the resulting liquid dispersion with the clay or clay-containing material via spraying, slurrying or other suitable methods. Suitable liquids for dispersion have a boiling point up to ca. 150 C. and include water, ketones, alcohols and hydrocarbon solvents, mixtures thereof and emulsions thereof, either oil-in-water or water-in-oil.

Because of the diverse nature of the MPP compounds utilized in the practice of this invention, some types of compounds are soluble, dispersible or emulsifiable in relatively hydrophilic media, others in relatively hydrophobic media. Upon inspection of a chemical formula, the art skilled can generally determine a solvent, dispersion medium or emulsifier satisfactory for a given MPP compound. In any event, the operability and desirability of a given solvent, dispersion medium or emulsifying agent can be determined by a simple test wherein a given MPP compound is dissolved, suspended or its solution emulsified in a given medium. Obviously, solvents, diluents and emulsifying agents are used which are inert toward the MPP compound. Hereinafter, such solutions, suspensions and emulsions will sometimes be referred to broadly as dispersions and the solvent, suspension and emulsion media will be referred to broadly as dispersion'media. Advantageously, the MPP compound dispersion contains between 0.0025 and 50 weight percent of MPP compound.

The treatment of the clay or clay-containing soil with the MPP compound should result in the clay or claycontaining soil containing at least 0.0025% and advantageously up to 2% by weight of the MPP compound, dry clay basis. The upper limit is essentially economic. The MPP compounds used for agricultural purposes need be applied only to the actual volume of soil being cultivated. Thus, when a MPP compound is used to decrease soil crusting, it is practical to treat only the soil immediately above the seed row. Depending upon how carefully the MPP compound is applied to this restricted volume of soil, anywhere from 0.1 pound to pounds of the MPP compound is sufiicient to treat one acre of crop land.

The modulus of rupture (MR) is a test to determine the maximum stress that a material will withstand without breaking and is determined by subjecting a rectangular briquette to a bending moment. This test is commonly accepted by soil scientists as a measure of the crusting potential of a soil and, hence, its relative suitability as an agricultural soil. The lower the maximum strieltss before rupture, the less the crusting potential of the so The MR was determined on an apparatus patterned after that as described and used by L. A. Richards in the Soil Science Society of America Proceedings, 17: 321- 323.

In each experiment conducted to obtain the test data, one control was included. The control was prepared exactly analogously to the other treatments except that no MPP compound was used.

The unconfined compressive strength (UCS) is a commonly accepted test used by civil engineers to determine the suitability of a soil to resist shear by stresses to which it will be subject. The UCS test data were obtained with MPP compounds using an unconfined compression testing apparatus manufactured by Soiltest Incorporated, model U-160. The rate of strain on the samples was about 0.07 inch per minute. The maximum stress which the samples could bear prior to failing was used to calculate the UCS of the sample via the method outlined in the manual provided by Soiltest Incorporated, entitled Unconfined Compression Testing of Cohesive Soils, dated 1957.

In each set of determinations conducted to provide the data for the following examples one control was included. A control was prepared in a manner exactly analogously to the other treatments except that no MPP compound was used.

The following examples describe completely specific embodiments and the best mode contemplated by the inventor for carrying out his invention. They are not to be construed as limiting the invention, which is defined in the claims.

EXAMPLE 1 A sample of finely ground, air-dried, slightly acid, clay loam soil was brought up to a moisture content of about 17% by spraying water as a fine mist onto the soil sample while subjecting it to thorough mixing. The MPP compound, as indicated in following Table I, was immediately added to the soil sample by spraying with and mixing in 5 to 10 ml. of an acetone solution containing 20 mg. of the MPP compound per 100 g. air-dried soil. This treatment provided a treated soil containing 200 ppm. of MPP compound on a dry soil weight basis.

Once the soil had been treated, it was allowed to stand in the open air for at least two hours and then was dried in an oven at 30 C. overnight. The heated soil was then divided into replicates of 25 to 30 g. each, the excess being disposed of, and placed into two rectangular molds 3.2 cm. wide by 6.4 cm. long. The soil in the molds was then leveled and compacted with a special compacting tool. The compacting tool has a base which covers the leveled soil sample and onto which was dropped a weight of 31.5 g. from a height of 31.5 cm. This weight was dropped repeatedly for six times, after which the soil was flooded with water. After the excess water had drained through the soil, the sample was dried overnight in an oven at 30 C. The resulting briquettes were then tested by the method cited above for their MR determinations with the following results.

The procedure of Example 1 was repeated with a similar soil sample and other MPP compounds with the following results.

Table II MPP Compound: MR in millibars Control 4450 6,6'-methylenedi-2,4-xylenol 1900 2,2'-ethy1idenebis(6-tert-butyl-p-cresol) 1700 .EXAMPLE 3 A mixture of 4 g. of Portland cement intimately mixed with g. of a finely ground, air-dried, slightly acid, clay loam soil was prepared. The mixture was then brought up to a moisture content of about 17% by spraying water as a fine mist onto the soil while subjecting the soil to additional mixing. The MPP compound, as indicated in following Table III, was immediately added to the soil sample by spraying with and mixing in 4 m1. of an acetone solution containing 80 mg. of the MPP compound. This treatment resulted in the soil containing 5% Portland cement and 0.1% MPP compound on a dry soil weight basis.

After the soil sample had ben treated, it was placed in a cylindrical molding tube 3 cm. in diameter and compressed from both ends in a hydraulic press at a pressure of 740 p.s.i. until a static condition was attained. The sample was then immediately ejected from the molding tube and placed in a relative humidity atmosphere to cure for a period of four days, followed by a one-day cure at room humidity. Next, the sample was immersed in water for one day, after which it was tested for UCS, as described above.

L r r-r EXAMPLE 4 The procedure of Example 3 was repeated with a similar soil sample and other MPP compounds, with the following results:

What is claimed is:

1. The method of treatment of clays and clay-containing soils containing at least 5 weight percent clay, dry basis, by admixing therewith a compound having the formula:

in which X is one of H and CH R and R individually are one of H and alkyl having up to 4 carbon atoms; R is one of H, Cl and alkyl having up to 4 carbon atoms; and n is an integer from 0 to 1, in amount sufiicient to provide at least 0.0025 and up to 2 weight percent of said compound, dry clay basis.

2. A composition of a clay material of the group consisting of clays and clay-containing soils containing at 6 least 5 weight precent clay, dry basis, and in admixture therewith at least 0.0025 and up to 2 weight percent, dry clay basis, of a compound having the formula:

R4 R R4 ltlxji 0 O H H nH in which X is one of H and CH R and R individually are one of H and alkyl having up to 4 carbon atoms; R is one of H, Cl, and alkyl having up to 4 carbon atoms; and n is an integer from 0 to 1.

3. The composition of claim 2'wherein the clay material contains at least 5 weight percent clay, dry basis, and from 1 to weight percent of at least one member of the group consisting of Portland cement, lime, asphalts and sodium silicates, dry clay basis.

4. The composition of claim 2 wherein the compound is 11 ,04 bis(5 tertbutyl 6 hydroxy m tolyl) 4- chloro-2,6-xylenol.

5. The composition of claim 2 wherein the compound is 6,6-methylenedi-2,4-xy1enol.

6. The composition of claim 2 wherein the compound is 2,2'-ethylidenebis(6-tert-butyl-p-cresol).

References Cited in the file of this patent UNITED STATES PATENTS 2,598,234 De Groote et al May 27, 1952 

2. A COMPOSITION OF A CLAY MATERIAL OF THE GROUP CONSISTING OF CLAYS AND CLAY-CONTAINING SOILS CONTAINING AT LEAST 5 WEIGH PERCENT CLAY, DRY BASIS, AND IN ADMIXTURE THEREWITH AT LEAST 0.0025 AND UP TO 5 WEIGHT PERCENT, DRY CLAY BASIS, OF A COMPOUND HAVING THE FORMULA:
 3. THE COMPOSITON OF CLAIM 2 WHEREIN THE CLAY MATERIAL CONTAINS AT LEAST 5 WEIGHT PERCENT CLAY, DRY BASIS, AND FROM 1 TO 100 WEIGHT PERCENT OF AT LEAST ONE MEMBER OF THE GROUP CONSISTING OF PORTLAND CEMENT, LIME, ASPHALTS AND SODIUM SILICATES, DRY CLAY BASIS. 